We run our ProIV Client as a "published application" on a Windows Terminal Server running Citrix Presentation Server (formerly called Metaframe) so that Macintosh computers and thin clients can access ProIV applications.

That's really quite interesting Fred. Would you mind clarifying a little for me as I don't use this stuff but I like to try and understand what's feasible (no offence taken if you don't have time for this).

The actual ProIV client (and hence any Active/X "dependencies" it has?) run on an MS-Windows box "under the control" of Citrix?
The Citrix ICA client program handles only the actual "painted" graphics and actual user input (mouse etc.) and communicates this stuff at a "low level" using some optimized protocol with the Citrix server? (Kind of like X/Windows?)
Does this mean good UI responsiveness typically depends on a LAN connection and things are less acceptable across an arbitrary internet connection?

To what extend does/can the presentation on Mac/Linux etc. have any native "look and feel" .. or does the ProIV GUI just look pixel-for-pixel like it would on Windows?

Is there any limit on the number of "end" users Citrix can support from one box?
How "big" a Citrix server box would you say is necessary for 100 ProIV GUI users?
Presumably you can just have a Citrix "presentation server" farm if you needed?
Roughly how much does Citrix add to the cost of the sytem in your experience?

Windows Terminal Server is, in effect, a multi-user Windows computer. Each user connects to the Windows Terminal Server from another PC or thin-client using the Microsoft Remote Desktop Connection client.

Each user gets his/her own desktop (i.e. a virtual windows session) just like working on a PC with Windows XP. Programs run by users in their virtual session actually execute on the server, not the client device. All users share the disk storage and other devices on the server.

The ProIV Client (proiv.exe) and piv files are installed once on the Windows Terminal Server/Citrix Presentation Server. Any client device (e.g. PC running MSDOS, PocketPC, Mac, Linux workstation, etc) connecting to the Windows Terminal Server/Citrix Presentation Server can then run any ProIV application just as if they had the ProIV Client installed on that device. Little or no difference in the UI of the application!

The ProIV Client is a relatively "thin" client program. It's primary job is painting the screen. The TS/Citrix client is very similar. Consequently, running the ProIV Client puts very little burden on the TS/Citrix Server. Performance is not an issue, even over dial-up modems.

We have 2 TS/Citrix servers (dual processor Pentium 4s) supporting an average of concurrent 60 users accessing 2 commercial ProIV applications. We have the 2 servers primarily for load balancing, redundancy and quick failover (we're a veterinary hospital open 7x24). Many times, we take one TS/Citrix Server off-line for maintenance, and the remaining TS/Citrix Server handles the entire load without any problems! We could easily support 100 users or more for our ProIV applications on a single TS/Citrix Server.

I don't know the current cost of Citrix Presentation Server. They have changed their pricing and licensing scheme over time (we've had it for 7 years). I believe that Citrix is now selling their products on a per user basis. You simply buy the licenses for the number of concurrent users you need to support.

The benefits:
1. We have PCs, Macs, and thin-clients all running ProIV applications.
2. We install and support the ProIV Client software on 2 computers (i.e. the 2 TS/Citrix Servers), not the +150 computers that can access our ProIV applications.
3. We can terminate/suspend users access to the ProIV applications by disabling TS/Citrix Services without shutting down our ProIV Server. This allows us to run critical processes or upgrade our ProIV applications without fear of any users doing other things at the same time.
4. We can "shadow" any user's session to assist them or trouble-shoot any problems from anywhere.

I hope that helps you understand how this works.

Fred

P.S. FYI: The same thin-client devices that our users use to access our ProIV applications are also running IE to view radiographic DICOM images across the same network. Network performance is just fine!